Rotary hydraulic machines

ABSTRACT

A hydraulic pump or motor in which a rotor has a plurality of pistons slidable in radial bores in the rotor. The pistons engage a cam ring surrounding the rotor, and the eccentricity of the cam ring can be varied by means of one or more servo pistons.

Umted States Patent 1191 1111 3,744,379

Freeman July 10, 1973 [54] ROTARY HYDRAULIC MACHINES 1,413,388 4/1922 Calhoun 91/498 [75] Inventor: Frank George Freeman, Solihull,

Warwickshire, England 2:855:858 10/1958 [73] Assignee: Joseph Lucas (Industries) Limited,

Brmmgham England 2:712:794 7/1955 l-lumphreys 91 /492 [22] 1971 FOREIGN PATENTS OR APPLICATIONS 1 PP 123,861 393,924 11/1965 Switzerland 91/498 [30] Foreign Application Priority Data Primary Examiner-William L. Freeh Apr. 3, 1970 Great Britain 15,808/70 & Stem 52 us. (:1. 91/497 57 1 ABSTRACT [51] int. Cl. F0lb 13/06 [58] Field of Search ..9l/49l-498 A hydraulw P p or motor In which a rotor has a P rality of pistons slidable in radial bores in the rotor. The pistons engage a cam ring surrounding the rotor, and

[ 56] References Cited the eccentricity of the cam ring can be varied by means UNITED STATES PATENTS of one or more servo pistons.

1,852,335 4/1932 Rosen 91/497 11 Claims, 3 Drawing Figures PATENTEL-JULIOIQTS 3,744,379

SHEET 1 at 5 INVENTOR F wmk 110x 1 Evgm PATENIEDJULIOISB 3,744,379

sum 2 or 3 FIG. 2

INVENTOR Fmk on owu ATTORNEYS PATENIEDJULIOIQYS 3 744,379

SHEET 3 [IF 3 INVENTOR ATTORNEYS ROTARY HYDRAULIC MACHINES BACKGROUND OF THE INVENTION This invention relates to rotary hydraulic machines such as pumps and motors and has as an object of the provision of such a machine in a convenient form.

SUMMARY OF THE INVENTION According to the invention, a rotary hydraulic machine comprises a casing, an internal pintle secured to the casing, a rotor carried on the pintle, a plurality of pistons in radial bores in the rotor, an annular member within the body, the pistons engaging the inner face of said member and a piston responsive to a servo pressure, the servo-responsive piston being slidable within the pintle and co-acting with the annular member to vary the eccentricity thereof with respect to the rotor.

A pump according to the invention will now be described by way of example and with reference to the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a section through a pump; and FIGS. 2 and 3 are views taken along 2-2 and 3--3 respectively in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION The pump has a casing formed in two parts 10,11 and the part 11 includes an integral stepped pintle 12. Within the pintle 12 are a pair of passages 13,14 which open onto the surface of the pintle 12 to provide ports 15,16 respectively. Mounted on the pintle 12 is a rotor 17 having a plurality of stepped radial bores 18 within each of which a piston 19 is slidable Secured by a stud 20 to each piston 19 is a slipper 21.

An annular member or cam ring 22 is carried within the casing 10, 11 and can engage a pin 23 which extends into the casing 10, 11. The member 22 is engageable by a pair of piston elements in the form of balls 24,25 which are slidable in respective bores 26,27 in the pintle 12. Bores 26,27 communicate via respective passages 28,29 with the outside of the casing part 11. A spring 30 engages the ball 24 to bias the annular member 22 in a clockwise direction as shown in FIG. 3 with respect to pin 23.

Rotor 17 includes a shaft 31 having a flanged portion 31a secured by dowels 32 to the remainder of the rotor 17. The casing part sealingly supports a bushing 33 on which is mounted a bearing ring 33a. Ring 33a slidably and sealingly engages the flanged portion 31a. Shaft 31 also passes through a bushing 34. A bearing ring 34a is mounted on the bushing 34 and engages a collar 35 sealingly secured to the shaft 31. The bushing 34 is sealingly supported by a disc 36 which is in turn sealingly engaged with the body part 10 so as to define an annular space 37 between the rings 33a, 340. A passage 38 provides a drain for the space 37. A spring washer 39 urges the bushings 33,34 apart andthereby urges the rings 33a,34a into sealing engagement with the flange 31a and collar 35 respectively.

In use, when the member 22 is eccentric with respect to the rotor 17, rotation of shaft 31 causes liquid to be drawn in through passage 13 and discharged through passage 14 in a known manner. Servo control pressures are applied to the passages 27,28. If the differece between the servo pressure is such as to overcome the bias applied by the spring 30, themember 22 is urged to roll about the surface of pin 23 in an anticlockwise direction as seen in FIG. 1. The eccentricity of member 22 with respect to the rotor 17, and hence the delivery of the pump for a given speed, may thus be varied. Since the interior of the casing communicates with the inlet passage 13, liquid in the casing is at low pressure and leakage past the ring 33a is small. Any such leakage is, however, drained away via passage 38.

It will be understood that an arrangement substantially as described may also be used as a hydraulic motor, in which case a fluid under pressure is applied to the passage 14 and permitted to exhaust via passage 13.

Having thus described my invention what I claim as new and'desire to secure by Letters Patent is:

l. A rotary hydraulic manhine comprising a casing, a pintle secured to and extending into the casing, a rotor rotatable about the pintle, a plurality of radial bores in the rotor, pistons reciprocable respectively in the bores, a cam ring within the casing surrounding the rotor and pistons, the pistons engaging the inner face of the cam ring and means for varying the eccentricity of the cam ring with respect to the rotor, said eccentricity varying means including a bore within the pintle, a piston responsive to a servo pressure slidable within the pintle bore and being cooperable with the cam ring to urge the cam ring in one direction to vary the eccentricity thereof with respect to the rotor.

2. The machine as claimed in claim 1 in which said servo piston is a ball.

3. The machine as claimed in claim 1 including a further servo-piston slidable in a further bore in the pintle, said further servo-piston being responsive to a further servo, pressure and coacting with said cam ring to urge the cam ring in a direction opposite to its movement in response to the first mentioned servo pressure.

4. The machine as claimed in claim 3 which includes biasing means acting on said further servo piston in support of said further servo pressure.

5. The machine as claimed in claim 3 in which said further piston is a ball.

6. The machine as claimed in claim 1 including a pro-' jection extending internally of said casing, about which projection said cam can roll under the influence of said servo responsive piston.

7. The machine as claimed in claim 1 in which each said piston in said radial bores includes a slipper engaging said cam ring.

8. The machine as claimed in claim 7 in which said slippers are secured to said pistons by studs.

9. The machine as claimed in claim 1 including a sealing arrangement on said casing through which said rotor extends.

10. The machine as claimed in-claim 9 in which said sealing arrangement comprises a pair of rings mounted on the casing and sealingly engaging said rotor, and means biasing said rings into engagement with said rotor.

11. The machine as claimed in claim 10 in which said rings define a chamber which communicates with a 

1. A rotary hydraulic manhine comprising a casing, a pintle secured to and extending into the casing, a rotor rotatable about the pintle, a plurality of radial bores in the rotor, pistons reciprocable respectively in the bores, a cam ring within the casing surrounding the rotor and pistons, the pistons engaging the inner face of the cam ring and means for varying the eccentricity of the cam ring with respect to the rotor, said eccentricity varying means including a bore within the pintle, a piston responsive to a servo pressure slidable within the pintle bore and being cooperable with the cam ring to urge the cam ring in one direction to vary the eccentricity thereof with respect to the rotor.
 2. The machine as claimed in claim 1 in which said servo piston is a ball.
 3. The machine as claimed in claim 1 including a further servo-piston slidable in a further bore in the pintle, said further servo-piston being responsive to a further servo, pressure and coacting with said cam ring to urge the cam ring in a direction opposite to its movement in response to the first mentioned servo pressure.
 4. The machine as claimed in claim 3 which includes biasing means acting on said further servo piston in support of said further servo pressure.
 5. The machine as claimed in claim 3 in which said further piston is a ball.
 6. The machine as claimed in claim 1 including a projection extending internally of said casing, about which projection said cam can roll under the influence of said servo responsive piston.
 7. The machine as claimed in claim 1 in which each said piston in said radial bores includes a slipper engaging said cam ring.
 8. The machine as claimed in claim 7 in which said slippers are secured to said pistons by studs.
 9. The machine as claimed in claim 1 including a sealing arrangement on said casing through which said rotor extends.
 10. The machine as claimed in claim 9 in which said sealing arrangement comprises a pair of rings mounted on the casing and sealingly engaging said rotor, and means biasing said rings into engagement with said rotor.
 11. The machine as claimed in claim 10 in which said rings define a chamber which communicates with a drain. 